According to our current understanding of physics based on the theory of relativity, it is impossible for an object with mass, such as a human being, to travel at the speed of light. As an object with mass approaches the speed of light, its relativistic mass increases, requiring an infinite amount of energy to reach the speed of light.
However, let's consider a thought experiment where we imagine a spacecraft traveling very close to the speed of light. In this scenario:
Time dilation: According to the theory of relativity, as an object approaches the speed of light, time dilation occurs. Time would appear to pass more slowly for the person inside the spacecraft relative to an observer on Earth. From the perspective of the person in the spacecraft, time would continue to pass normally, but they would perceive time on Earth to be moving much faster.
Length contraction: Another consequence of approaching the speed of light is length contraction. Objects in the direction of motion would appear compressed or contracted from the perspective of the person in the spacecraft. This contraction effect becomes more significant as the speed approaches the speed of light.
Increased energy requirements: As the spacecraft approaches the speed of light, the amount of energy required to accelerate it further becomes exponentially large. Therefore, reaching the speed of light would require an infinite amount of energy, which is not attainable.
It's important to note that these effects are theoretical and cannot be directly observed or experienced by objects with mass in our everyday lives. They are predictions based on the principles of relativity.